Instruments for sampling and measuring particulate matter in air are useful for a variety of purposes. They can be used for scientific research to study the nature of a particulate air pollutant and its transport and dispersion in the ambient atmosphere. They are also useful for studying the effect of a particulate air pollutant on human health. In addition, such instruments can also be used for sampling and measuring airborne particulate matter for regulatory compliance purposes to determine if the ambient level is within safe limits prescribed by law.